1. Field of the Invention
The present invention relates to a photoelectric encoder for use in precise measurement, a scale incorporated in the photoelectric encoder as an element, and a method of manufacturing the scale.
2. Description of the Prior Art
A photoelectric encoder has been utilized in the art for precise measurement of linear displacement, angular displacement and the like. There are many types of photoelectric encoders. For example, it is proposed one type of photoelectric encoder that includes: a photoreceiver in which a plurality of photodiodes are arranged in an array manner; a scale disposed so as to be allowed to move relative to the photoreceiver and in which a reflection type of phase grating is formed; and a light source that emits light to the phase grating (See Japanese Patent Application Publication No. 10-163549, for example). In such a photoelectric encoder, signal light reflected and generated at the phase grating of the scale is received by the photoreceiver so that an amount of displacement such as liner displacement is calculated using an electric signal generated by photoelectric conversion of the signal light.
Since the signal light received by the photoreceiver is generated by the phase grating of the scale, the phase grating is an extremely important element of such a photoelectric encoder. Thus, it is desired means for easily manufacturing a phase grating with high precision.
Although it is thought that the grating of the scale may be formed with high density in order to achieve the phase grating with high precision, there is a problem that the costs of manufacturing the scale with high density are increased.